1. Field of the Invention
The present invention relates to the field of suspension thrust bearing devices used, in particular, in the suspension struts of the steered wheels of motor vehicles.
2. Description of the Relevant Art
Conventionally, a suspension thrust bearing is provided with an upper race and a lower race, between which rolling elements are arranged, and with lower and upper bearing or support elements, such as caps, forming housings for the lower and upper races of the rolling bearing respectively.
A suspension thrust bearing is arranged in the upper part of the suspension strut between a suspension spring and an upper element which is fixed to the vehicle body. The suspension spring is arranged around a damper piston rod whose end can be secured to the vehicle body. The spring bears axially, directly or indirectly, on the lower support cap of the rolling bearing.
The suspension thrust bearing thus makes it possible to transmit axial forces between the suspension spring and the vehicle body while permitting a relative angular movement between the lower cap, which can move rotationally, and the upper cap. This relative angular movement can result from the steered wheels being turned and/or from the suspension spring being compressed.
Document GB-A-2 347 906 discloses a suspension thrust bearing provided with a support cap and with a rolling bearing mounted on the support cap.
The support cap is made of synthetic material, and includes an axial centering surface for a suspension spring, this surface being extended outwardly at its upper end by a helical surface forming a stop for the upper end turn of the spring.
This suspension thrust bearing has the disadvantage of including a support cap on which the upper end of the spring bears directly. Thus, the vibrations of the spring are transmitted to the motor vehicle body via the support cap, this being detrimental to vehicle comfort.
With the aim of limiting these phenomena, it is desirable for such vibrations to be absorbed, at least in part.
In this respect, and as illustrated in FIG. 2 of document FR-A-2 809 675, it is possible to provide a suspension thrust bearing having a flexible elastomeric baseplate mounted on the support cap and provided with a bearing surface for the spring.
However, such a suspension thrust bearing has certain disadvantages.
Specifically, a suspension thrust bearing is generally exposed to various kinds of pollution, especially to splashing water droplets when the motor vehicle is traveling along a wet road, these droplets being directed towards the thrust bearing by the aerodynamic turbulence generated by the movement of the vehicle.
However, with the suspension thrust bearing provided in that document, such water droplets can easily be directed towards the rolling bearing and be introduced inside the latter.
Under these conditions, it will readily be appreciated that there are thus significant risks of polluting elements, which can lead to possible malfunctioning, being introduced inside the suspension thrust bearing.